Abstract The objectives of this research were to determine the contribution of excitation-contraction (E-C) coupling failure to the decrement in maximal isometric tetanic force (P o ) in mouse extensor digitorum longus (EDL) muscles after eccentric contractions and to elucidate possible mechanisms. The left anterior crural muscles of female ICR mice ( n = 164) were injured in vivo with 150 eccentric contractions. P o , caffeine-, 4-chloro- m -cresol-, and K + -induced contracture forces, sarcoplasmic reticulum (SR) Ca 2+ release and uptake rates, and intracellular Ca 2+ concentration (Ca 2+ i ) were then measured in vitro in injured and contralateral control EDL muscles at various times after injury up to 14 days. On the basis of the disproportional reduction in P o (∼51%) compared with caffeine-induced force (∼11–21%), we estimate that E-C coupling failure can explain 57–75% of the P o decrement from 0 to 5 days postinjury. Comparable reductions in P o and K + -induced force (51%), and minor reductions (0–6%) in the maximal SR Ca 2+ release rate, suggest that the E-C coupling defect site is located at the t tubule-SR interface immediately after injury. Confocal laser scanning microscopy indicated that resting Ca 2+ i was elevated and peak tetanic Ca 2+ i was reduced, whereas peak 4-chloro- m -cresol-induced Ca 2+ i was unchanged immediately after injury. By 3 days postinjury, 4-chloro- m -cresol-induced Ca 2+ i became depressed, probably because of decreased SR Ca 2+ release and uptake rates (17–31%). These data indicate that the decrease in P o during the first several days after injury primarily stems from a failure in the E-C coupling process. excitation-contraction extensor digitorum longus fluo 3 fura red calcium-selective minielectrode Footnotes Address for reprint requests: C. P. Ingalls, Muscle Biology Laboratory, Dept. of Health and Kinesiology, Texas A&M Univ., College Station, TX 77843-4243 (E-mail: Ingalls@unix.tamu.edu ). Copyright © 1998 the American Physiological Society
Journal of Applied Physiology – The American Physiological Society
Published: Jul 1, 1998
It’s your single place to instantly
discover and read the research
that matters to you.
Enjoy affordable access to
over 18 million articles from more than
15,000 peer-reviewed journals.
All for just $49/month
Query the DeepDyve database, plus search all of PubMed and Google Scholar seamlessly
Save any article or search result from DeepDyve, PubMed, and Google Scholar... all in one place.
Get unlimited, online access to over 18 million full-text articles from more than 15,000 scientific journals.
Read from thousands of the leading scholarly journals from SpringerNature, Wiley-Blackwell, Oxford University Press and more.
All the latest content is available, no embargo periods.
“Hi guys, I cannot tell you how much I love this resource. Incredible. I really believe you've hit the nail on the head with this site in regards to solving the research-purchase issue.”Daniel C.
“Whoa! It’s like Spotify but for academic articles.”@Phil_Robichaud
“I must say, @deepdyve is a fabulous solution to the independent researcher's problem of #access to #information.”@deepthiw
“My last article couldn't be possible without the platform @deepdyve that makes journal papers cheaper.”@JoseServera